The binding energy and the trapping cross-section of cluster dipole states in a high purity germanium detector operated at cryogenic temperature.

We have studied the charge trapping in germanium detectors at 5.2 K and calculated the binding energy of cluster dipole states and the electric field dependent trapping cross section. Two planar detectors, a p-type and a n-type detector are used in this study. Detectors are operated in two different modes: the first method is to deplete the detector at 77k and then decrease temperature to 5.2K and the second method is directly to decrease the detector temperature to 5.2 k and then apply different bias voltages. It is found that the binding energy of cluster dipole states is lower in the second method than in the first method. It indicates the different charge states to begin with in the detector. The binding energy of the trapped charge carriers in cluster dipole states is found in the range of ~5-8 meV.